Caustic Soda (Sodium Hydroxide) Testing Procedure

Determination of alkaline content by titration procedure or caustic soda (Sodium hydroxide) purity analysis procedure and purity of NaOH ( sodium hydroxide) pellets. 


a). 250ml conical flask.

b). Burette

c). 25 ml volumetric pipette

d). 250ml volumetric flask


a). Standard 0.1(N) HCl solution

b). Phenolphthalein indicator

c). Methyl orange indicator

Assay Procedure of Caustic Soda 

Accurately weigh out approx 1.5195 gms. of caustic soda sample in a 250 ml volumetric flask. Make up to the mark with distilled water and shake well to make a solution. 

Remove a 25 ml portion of this solution in a 250ml conical flask and titrate with 0.1(N) HCl solution from a burette using a phenolphthalein indicator. Note the burette reading at this point.

\[\text"Total alkalinity" (%) = (V1 * N) / W\]

\[ = x(%)\]                                 

Now add Methyl Orange solution to this colorless solution in the conical flask. 

Continue titration till the orange color changes to red at the endpoint. Note the burette reading (V2 ).

\[\text"Alkalinity as  Na2CO3" (%) = {V2 – V1 (ml) * N * 5.3} / {Weight}\]

\[= y%\]

Assay of caustic soda = (x-y) %

Uses of Sodium Hydroxide

Caustic soda, also known as sodium hydroxide (NaOH), is a chemical compound with a wide range of uses in various types industries.

1. It is a fundamental ingredient in the production of various chemicals, like detergents, soaps, and cleaning agents. 

2. Caustic soda is used in the pulping process to break down lignin and separate fibers from wood. 

3. It is used in the textile industry to remove natural fats, oils, and waxes from fabrics. 

4. It is used to dissolve alumina (aluminum oxide) from bauxite ore during the production of aluminum. 

4. It helps to remove impurities, such as sulfur compounds, from crude oil and improves the quality of the end products.

6. In food processing, caustic soda is used for cleaning and sanitizing equipment and containers. 

7. Caustic soda is used in water treatment plants to adjust the pH levels of water. 

8. Household cleaning agents often contain caustic soda due to its ability to dissolve grease, oils, and other tough stains. 

9. It is used in the transesterification process to convert vegetable oils or animal fats into biodiesel and glycerol.

10. Caustic soda is used in the dyeing process to prepare fabrics for dye absorption. 



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